I think that you Will like the 4.2 update for the iPad.It brings some good things, but it will also change yur rotation screen lock to a mute switch.If this isn't too bad for you I think you will be happy with the update.
You can change both wallpapers, the one from unlock screen and even the one from your home screen, just like on the iPhone with iOS 4.
And you can download a wallpaper from google images.